The 2.4 GHz Industrial, Scientific, and Medical (ISM) Band provides unlicensed spectrum which is uniquely available throughout the world. In the U.S. it is governed by Federal Communications Commission (FCC) parts 15.209 and 15.247. In Europe, the European Telecommunications Standardization Institute (ETSI) ETS 300.328 outlines its requirements. In Japan, certain standards cover the band. Most of the rest of the world has also designated this band for common use. The dominant application of this frequency band is for consumer microwave ovens which on one-hand guarantees the continued existence of the band but on the other hand is a significant source of interference. This interference is bursty in nature. In spite of this challenge, this band provides an opportunity for in-home networks to develop one platform for universal deployment allowing the greatest economy of scale to be leveraged. However, other bands exist with similar interference characteristics that may also be useful for in-home networks.
The Digital European Cordless Telephone (DECT) system, the Personal Handyphone System (PHS), and other micro-cellular systems have been suggested for in-home applications and, at first glance, seem suitable with respect to the systems' integral cordless telephone function. However, the current frequency plans for DECT and PHS are only available regionally. Furthermore, rules governing the 2.4 GHz ISM, the only band with worldwide availability, is not conducive to PHS or DECT protocols. Both PHS and DECT cannot withstand the bursted interference. Interference aside, these micro-cellular systems contain significant additional complexity to handle community or campus deployment providing for intercell handoff and roaming capability. Similarly, the systems are designed to tolerate multipath distortion present even in the systems' small micro-cell environment which is significantly larger than an in-home pico-cell.
Thus there is a need for a low complexity protocol, device and system that is robust in the presence of bursted interference.